The purpose is to provide a basis for new methods of diagnosing and evaluating laryngeal control of phonation from measurements which can be made rapidly, economically, and without risk to the patient, in the typical speech clinic. Techniques such as electroglottography, photoglottography, ultrasonic transmission through the larynx, and inverse filtering of the acoustic speech waveform, recently have been developed and used for research on speech production. These techniques would also be useful as diagnostic tools for normal and abnormal phonation provided that their output waveforms were interpretable in terms of vocal physiology. In order to investigate the possibility of such interpretation, we propose to use a computer model of the vocal folds and larynx to relate physiological control of phonation to model-synthesized versions of these waveforms, allowing us to determine the control-information content in each waveform. Electromyographic (EMG) measurements will be made to test the validity of the model and investigate the feasibility of finding a generalized function relating actual waveforms to control tensions of the laryngeal muscles. A parameterization of the glottal waveforms will be derived, from which regression into the physiological control domain will be attempted on a statistical basis for many synthesized waveforms, and for waveforms recorded during phonation by normal speakers and speakers having abnormal phonation. If the methods prove successful, they would provide a basis for greatly improved diagnosis and therapy for phonation deficiencies that originate in abnormal laryngeal control, and for phonation-training of the normal voice.